With his 1974 rape conviction recently thrown out by a judge, Wilbert Jones of Louisiana walked out of the East Baton Rouge Parish Prison this week after nearly half a century behind bars.

Freed on $2,000 bail on Wednesday, Mr. Jones, 65, greeted family members in the prison’s parking lot, where he smiled and told reporters that he was ready to “enjoy life” and “praise God.”

His release was years in the making. But he could still return to prison if the state’s plan to appeal a District Court judge’s decision to vacate Mr. Jones’s conviction is successful.

In 1971, a nurse, identified in court documents as A. H., was raped in the parking lot of the hospital where she worked in Baton Rouge. Months later, she identified Mr. Jones out of a lineup as her attacker. He was 19 when he was arrested, and the victim’s testimony eventually led to a conviction and a life sentence without parole.

Mr. Jones has maintained his innocence.

In 2003, Innocence Project New Orleans, a nonprofit law office, began looking into the case and was instrumental in bringing it to the attention of the Louisiana Supreme Court, which referred it to the state’s District Court.

In October, Judge Richard D. Anderson of Louisiana District Court ruled that because important evidence had been withheld from the defense at trial — specifically, that another man who fit the description of the suspect was accused of committing similar crimes in the same area — Mr. Jones’s conviction should be vacated.

“This Court finds that the State’s case against Jones was weak, at best,” Judge Anderson wrote in his ruling. “There was no forensic or physical evidence linking Jones to the rape of A. H. The State’s case against Jones rested entirely on A. H.’s testimony and questionable identification.” He added that the victim expressed uncertainty about her identification at the time of the trial.

In a phone interview, Emily Maw, the director of Innocence Project New Orleans, noted that “an unsure identification was enough to send a young black man away for the rest of his life without the possibility of parole.” She said the 1974 conviction was not necessarily the result of any individual prosecutor withholding evidence with malicious intent.

“It is an entire system that does not think it needs to take the care to make sure that these criminal investigations and trials are as accurate as they can possibly be,” she said.

But prosecutors intend to appeal the decision to vacate Mr. Jones’s conviction; if the appeal is successful, he could be sent back to prison for the rest of his life.

In an emailed statement, Hillar C. Moore III, the East Baton Rouge district attorney, said his office would be filing an appeal by Dec. 1 in an effort to “continue to seek justice for the victim,” who died in 2008.

He added: “Two juries heard the evidence and heard and saw this victim testify and identify her attacker after being subjected to a brutal abduction and repeated rapes. The victim was with her attacker for at least an hour and was able to clearly see and later identify as well as speak with him.”

But on Wednesday, Mr. Jones told reporters he had been imprisoned for something he didn’t do. “I’m going to get out there and speak to the young kids,” he said, adding, “Go the right way, and trust in God.”

Ms. Maw said Mr. Jones “got a very good night’s rest” as he adjusted to freedom after 45 years and 10 months behind bars. “He is calm, grateful, humble and has developed a strength and a patience that I think most people could not even begin to understand.”

A version of this article appears in print on , on Page A30 of the New York edition with the headline: Conviction Tossed, Man Is Free After 45 Years . Order Reprints | Today’s Paper | Subscribe